I've asked this elsewhere and will continue to do so until I'm lucky enough to find someone who knows – How do the various newly released Dark Age rules compare? (SAGA, Dux Brit and Dux Bell, & Comitatus).

By "fantasy" you mean "alternative history-ish" as opposed to "dragons and beasties and orcy type fantasy", right

JJ: I've only played SAGA and Dux Brit. SAGA is for the "Viking Age", so Lindisfarne to Hastings. The real game lies not on the board, but on the battleboards. You have to use your "saga dice" correctly to unlock special abilities or extra combat dice. The mechanics are simple, but the battle boards are what give the game its complexity and the armies their individual flavour. It's a defiantly skirmish level game.

Dux Brit is a game that can be played either at army-level or "company level", depending on if you're doing a raid or a battle scenario. It runs pretty much like all Lardy games, but with period chrome to make it more Dark Age. As Rich Clarke says, it's less medieval and a lot more like the last gasp of ancient warfare.